We should confirm our signals
There are countless signals that we base our decisions on. Few of them stand up to critical scrutiny. I believe that conviction should follow confirmation. Let's take the random chance out of our success and understand the value of our tools.
A cursory glance at sites such as stockcharts.com, Investopedia, and Trading View reveals countless signals and strategies that are offered without any experimental evidence. Testing these approaches is typically done with backtesting: simulated trading with the end results presented as profit and loss.
I believe in backtesting only after we have statistical confirmation that the effect is real and something like causation exists. It's very difficult to get absolute answers out of statistical tests, but it is the least we should do before risking our money.
Past performance is not indicative of future results. If you don't have a statistical basis in your approach, your assurance of future results should be very poor.
Backtest if you must, but you might be surprised at how easy some basic statistical tests are.